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prometheus.exporter.postgres

The prometheus.exporter.postgres component embeds the postgres_exporter for collecting metrics from a PostgreSQL database.

Multiple prometheus.exporter.postgres components can be specified by giving them different labels.

Usage

alloy Copy

prometheus.exporter.postgres "LABEL" {
    data_source_names = DATA_SOURCE_NAMES_LIST
}

Arguments

The following arguments are supported:

Refer to the PostgreSQL documentation for more information about the format of the connection strings in data_source_names.

Refer to the examples for the custom_queries_config_path file in the postgres_exporter repository.

By default, the same set of metrics is enabled as in the upstream postgres_exporter. If custom_queries_config_path is set, additional metrics defined in the given configuration file will be exposed. If disable_default_metrics is set to true, only the metrics defined in the custom_queries_config_path file will be exposed.

A subset of metrics collectors can be controlled by setting the enabled_collectors argument. The following collectors are available for selection:

• database
• database_wraparound
• locks
• long_running_transactions
• postmaster
• process_idle
• replication
• replication_slot
• stat_activity_autovacuum
• stat_bgwriter
• stat_database
• stat_statements
• stat_user_tables
• stat_wal_receiver
• statio_user_indexes
• statio_user_tables
• wal
• xlog_location

By default, the following collectors are enabled:

• database
• locks
• replication
• replication_slot
• stat_bgwriter
• stat_database
• stat_user_tables
• statio_user_tables
• wal

Blocks

The following blocks are supported:

autodiscovery block

The autodiscovery block configures discovery of databases, outside of any specified in data_source_names.

The following arguments are supported:

If enabled is set to true and no allowlist or denylist is specified, the exporter will scrape from all databases.

If autodiscovery is disabled, neither database_allowlist nor database_denylist will have any effect.

Exported fields

The following fields are exported and can be referenced by other components.

For example, the targets can either be passed to a discovery.relabel component to rewrite the targets’ label sets or to a prometheus.scrape component that collects the exposed metrics.

The exported targets use the configured in-memory traffic address specified by the run command.

Component health

prometheus.exporter.postgres is only reported as unhealthy if given an invalid configuration.

Debug information

prometheus.exporter.postgres doesn’t expose any component-specific debug information.

Debug metrics

prometheus.exporter.postgres doesn’t expose any component-specific debug metrics.

Examples

Collect metrics from a PostgreSQL server

This example uses a prometheus.exporter.postgres component to collect metrics from a PostgreSQL server running locally with all default settings:

alloy Copy

// Because no autodiscovery is defined, this will only scrape the 'database_name' database, as defined
// in the DSN below.
prometheus.exporter.postgres "example" {
  data_source_names = ["postgresql://username:password@localhost:5432/database_name?sslmode=disable"]
}

prometheus.scrape "default" {
  targets    = prometheus.exporter.postgres.example.targets
  forward_to = [prometheus.remote_write.demo.receiver]
}

prometheus.remote_write "demo" {
  endpoint {
    url = PROMETHEUS_REMOTE_WRITE_URL

    basic_auth {
      username = USERNAME
      password = PASSWORD
    }
  }
}

Replace the following:

• PROMETHEUS_REMOTE_WRITE_URL: The URL of the Prometheus remote_write-compatible server to send metrics to.
• USERNAME: The username to use for authentication to the remote_write API.
• PASSWORD: The password to use for authentication to the remote_write API.

Collect custom metrics from an allowlisted set of databases

This example uses a prometheus.exporter.postgres component to collect custom metrics from a set of specific databases, replacing default metrics with custom metrics derived from queries in /etc/alloy/custom-postgres-metrics.yaml:

alloy Copy

prometheus.exporter.postgres "example" {
  data_source_names = ["postgresql://username:password@localhost:5432/database_name?sslmode=disable"]

  // This block configures autodiscovery to check for databases outside of the 'database_name' db
  // specified in the DSN above. The database_allowlist field means that only the 'frontend_app' and 'backend_app'
  // databases will be scraped.
  autodiscovery {
    enabled            = true
    database_allowlist = ["frontend_app", "backend_app"]
  }

  disable_default_metrics    = true
  custom_queries_config_path = "/etc/alloy/custom-postgres-metrics.yaml"
}

prometheus.scrape "default" {
  targets    = prometheus.exporter.postgres.example.targets
  forward_to = [prometheus.remote_write.demo.receiver]
}

prometheus.remote_write "demo" {
  endpoint {
    url = PROMETHEUS_REMOTE_WRITE_URL

    basic_auth {
      username = USERNAME
      password = PASSWORD
    }
  }
}

Replace the following:

• PROMETHEUS_REMOTE_WRITE_URL: The URL of the Prometheus remote_write-compatible server to send metrics to.
• USERNAME: The username to use for authentication to the remote_write API.
• PASSWORD: The password to use for authentication to the remote_write API.

Collect metrics from all databases except for a denylisted database

This example uses a prometheus.exporter.postgres component to collect custom metrics from all databases except for the secrets database.

alloy Copy

prometheus.exporter.postgres "example" {
  data_source_names = ["postgresql://username:password@localhost:5432/database_name?sslmode=disable"]

  // The database_denylist field will filter out those databases from the list of databases to scrape,
  // meaning that all databases *except* these will be scraped.
  //
  // In this example it will scrape all databases except for the one named 'secrets'.
  autodiscovery {
    enabled           = true
    database_denylist = ["secrets"]
  }
}

prometheus.scrape "default" {
  targets    = prometheus.exporter.postgres.example.targets
  forward_to = [prometheus.remote_write.demo.receiver]
}

prometheus.remote_write "demo" {
  endpoint {
    url = PROMETHEUS_REMOTE_WRITE_URL

    basic_auth {
      username = USERNAME
      password = PASSWORD
    }
  }
}

Replace the following:

• PROMETHEUS_REMOTE_WRITE_URL: The URL of the Prometheus remote_write-compatible server to send metrics to.
• USERNAME: The username to use for authentication to the remote_write API.
• PASSWORD: The password to use for authentication to the remote_write API.

Compatible components

prometheus.exporter.postgres has exports that can be consumed by the following components:

• Components that consume Targets